In conventional abrasive blast cleaning systems wherein a suitable blast media as particulate sand is forcibly directed from a nozzle under air pressure or by centrifugal force against and around a workpiece to scour and clean the same, it is highly desirable and indeed frequently necessary to insure that successive like workpieces, as molded metal parts, are subjected to the same amount and intensity of sand blast to insure generally uniform and like scouring on all like workpieces by the abrasive media. Heretofore, no simple yet effective means has been available in the marketplace.